Major League Baseball distributed a memo to clubs Friday informing them that rules regarding the use of foreign substances by pitchers will continue to be strictly monitored and enforced during the 2022 season.

In addition to checks of their glove, hat and belt by umpires, pitchers will now be subject to having their fingers and hands inspected at random points throughout the game.

“We want to thank the players for their cooperation last season and the umpires for doing an outstanding job of carrying out enforcement of the rule with great professionalism,” said Michael Hill, MLB senior vice president of on-field operations. “We saw a clear positive impact on the field with more balls in play, more action in the game, more runs scored and a return to the art of pitching with fewer strikeouts. We are encouraged the game moved in the right direction towards the version of baseball that our fans have told us they want to see. Moving forward, umpires have been given additional guidance to help them determine whether a pitcher’s hand or fingers contain a foreign substance in violation of the rules, which will make inspections more effective, and less invasive.”

Last season, MLB implemented enhanced monitoring and enforcement of the rules, increasing the monitoring of club spaces, documenting and inspecting baseballs taken out of play, and analyzing game video and Statcast data related to spin rate. The memo stated that by June, it became clear that the enhanced monitoring had “little or no impact on the behavior of many pitchers.”

With the use of foreign substances “more prevalent” than the league had anticipated, MLB instructed umpires as of June 21 to begin performing periodic checks throughout the game on both starters and relievers.

According to the memo, the checks produced an initial dip in spin rates, but data suggests that spin rates started to rise toward the end of the season as players grew accustomed to the circumstances of routine umpire checks.

As a result, umpires have been instructed to be “more vigilant and unpredictable in the timing and scope” of their checks during the 2022 season.

Starting pitchers will likely be checked more than once per game, while relievers will be checked upon entering a game or at the end of the inning. In general, inspections will be conducted between innings or after pitching changes to avoid a delay of the game.

Umpires will have the discretion to inspect any part of the player’s uniform, also determining if anything on a pitcher’s hand or fingers constitutes a foreign substance.

Per the memo, MLB is working with umpires this spring to make inspections less invasive. That could mean less focus on uniforms and belts and more on hands and fingers. Umpires will inspect the top and bottom of the pitching hand, looking for stickiness on the pitcher’s thumb, index finger, middle finger and palm.

Should an inspection reveal that the pitcher’s hand is, in the words of the memo, “unquestionably sticky,” the umpire will conclude that a foreign substance had been used in order to gain a competitive advantage, resulting in penalties.

Should an umpire observe a pitcher attempting to wipe off his hands prior to an inspection, the pitcher may be subject to immediate ejection for violating the rules by attempting to conceal a foreign substance. Catchers and position players may also be subject to inspections based on the circumstances.

Managers may continue to request an inspection if they observe behavior on the field consistent with use of a foreign substance, though that check will not take place until the end of the current at-bat. Managers will be subject to ejection and/or discipline if they make a request that is determined to be in bad faith.

Pitchers will continue to be permitted to use a rosin bag on their hand, wrist and forearm to assist in managing sweat, but they are prohibited from applying it to their gloves and uniforms, nor are they allowed to combine rosin with any other substance, such as sunscreen.

Pitchers will be permitted to carry a small wet rag in their back pocket to apply water to their pitching hand, though they may not access the rag while on the pitching rubber and must clearly wipe the fingers of the pitching hand dry before touching the ball or the rubber.

Any pitcher who possesses or applies foreign substances will be subject to immediate ejection from the game and suspended automatically in accordance with the rules. If a player other than the pitcher is found to have applied a foreign substance to the ball, both the position player and pitcher will be ejected. Position players will not be ejected for having a foreign substance on their glove or uniform unless the umpire determines that the player was applying the substance to the ball in order to aid the pitcher.

Players found to have used a foreign substance following a prior suspension for violating the rule will be subject to more severe penalties for each subsequent violation.

Teams will also be held accountable for any foreign substances discovered in any area such as the clubhouse, tunnel, dugout or bullpen.